The present invention relates to a laparoscopic instrument and more particularly to a laparoscopic instrument having an operable tip which is disposable, and/or replaceable, the tip comprising a set of cutting blades, forceps, or the like the operation of which is controlled and actuated manually.
A wide variety of instruments are presently known which are employed in the art of laparoscopic surgery, that is a species of endoscopic surgery which involves accessing a patient's peritoneal cavity by way of an endoscope passing through the patient's abdominal wall. Such medical instruments may take the form of cutting blades, forceps or other devices wherein the device is passed through a discrete opening providing access to the patient's organs, which opening may either be surgically created or naturally occurring. In such devices the surgeon must be able to manipulate adequately the internally disposed end of the laparoscopic instrument to perform the required surgical routine. Such devices therefore are often designed such that a movable rod may be manipulated at the rear, or operative end of the instrument to manipulate the instrument whether it be forceps, scissor-type blades or the like at the forward end of the laparoscopic device.
It has been found that in particular medical instruments, such as those employing cutting blades, it is necessary to replace the blades by new and sharper blades in which case it is economically feasible to merely remove the tip of the instrument and replace it with a new tip, rather than discarding the entire instrument.
In a device which is rod actuated as discussed above, a rod portion of the newly replaced tip must essentially be connected to a mating rod of the actuator, and the outer shell of the actuator upon which the tip is to be assembled attached to the tip shell in such relation that proper movement of the instrument occurs, with movement of the rod assembly within the actuator shell, or outer casing. It has been found expedient to employ a thread engagement between the actuator rod and the tip rod as well as a thread engagement between the outer shells or casings of the tip and actuator body to ensure a positive attachment of both outer casing and rod arrangements to permit operation of the instrument in the proper manner with the new tip. It is also essential that the removal and replacement of a tip require no special mechanical knowledge or capability on the part of the operator of the instrument, and that it may be done quickly and with a high degree of reliability.
In an arrangement as set forth above a problem arises in the initial engagement of the first threads in beginning the attachment of the new tip to the instrument. Normally, one would attempt to design such engagement by precise entering of the thread alignment both axial and angular such that the first entering threads both on the rod and shell attachment start exactly together, and once engaged would proceed threading one on the other to complete the attachment. However, this procedure has found to be both expensive and require a great deal of precision in design.
It is therefore an object of the present invention to provide a laparoscopic instrument assembly having a disposable tip wherein a tip rod is disposed for axial movement within a tubular tip casing structure, the tip rod and casing structure containing threads for attachment, in which the attachment is simple in construction and inexpensive to produce.
A further object of the invention is to provide a laparoscopic instrument assembly of the type described above wherein a precise angular and axial alignment is unnecessary when assembling the tip onto the instrument assembly.
Another object of the invention is to provide a laparoscopic instrument assembly of the type described wherein a replaceable tip is easily and quickly assembled onto the instrument assembly without requiring special instructions to the user.